CN115926785A - Scintillator layer material, flexible scintillator panel, preparation method and application thereof - Google Patents
Scintillator layer material, flexible scintillator panel, preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses a scintillator layer material, a flexible scintillator panel, a preparation method and application thereof, and relates to the technical field of radiation detectors. The scintillator layer material comprises a phosphor and a binder, the phosphor comprises a rare metal-doped inorganic compound, the two-dimensional structure of the phosphor comprises any one of a polygon and a circle, the binder comprises a resin precursor, and the refractive index of the resin precursor is larger than or equal to 1.52. By controlling the shape and structure of the phosphor, the phosphor can be arranged more closely when forming the scintillator layer, thereby reducing the interface distance, improving the filling density and avoiding the layering phenomenon of the scintillator particles. In addition, by selecting a resin precursor having a high refractive index as the binder, the problem of light scattering at the "particle-binder-particle" interface due to the difference in optical properties between the binder and the phosphor can be reduced, and the overall emission intensity of the scintillator layer can be improved.
Description
Technical Field
The invention relates to the technical field of radiation detectors, in particular to a scintillator layer material, a flexible scintillator panel, a preparation method and application thereof.
Background
Currently, an X-ray image sensor has been applied in large scale in the fields of medical imaging, nondestructive testing and the like, and is a key part of the whole imaging system. Conventionally, a photosensitive film interacts with X-rays to cause a photochemical reaction of a photosensitive substance in the film, and after development, X-ray intensity information of an object to be detected is recorded, so as to obtain internal structure information of the object, which is a purely analog image recording mode. Today, people use flat panel detectors to obtain digitized image information of an object. Generally, a flat panel detector converts incident X-rays into visible light by using a scintillator layer, converts the visible light into electric signals by using a matrix photodiode, reads the signals one by one under the control of a thin film transistor connected with the photodiode, and finally reconstructs the signals into digital images by a computer. The digital imaging mode greatly facilitates the development of a digital whole machine system, and can realize the analysis, interpretation and propagation of online or real-time detection results. As the core of the flat panel detector, the conversion efficiency of X-rays and visible light in the scintillator panel directly determines the performance of the whole detector, such as sensitivity, dynamic range and resolution.
At present, methods for preparing a scintillator panel mainly include a vacuum thermal evaporation method and a polymerization curing method, wherein the vacuum thermal evaporation method can obtain a columnar crystal scintillator layer by controlling a fine process, but the method requires a vacuum cavity matched with the size of a substrate, and the deposition of the scintillator layer under a high vacuum condition requires high cost. The polymerization curing method is to mix the scintillator particles with auxiliary materials such as a curing agent, a dispersing agent, an anti-settling agent, a stabilizing agent, a binder and the like, because the bonding capability of the auxiliary materials and the scintillator particles is poor, the layering phenomenon of the scintillator particles is easy to occur on a scintillator panel, meanwhile, the auxiliary materials such as the binder and the like do not have the luminous characteristic, a particle-binder-particle interface can be formed structurally, when light is transmitted on the interface, the phenomena of scattering, reflection, refraction and the like can be caused in the transmission process due to the difference of the optical performance of the scintillator particles and the binder, and total reflection can also occur in serious cases, so that the whole luminous efficiency of the scintillator panel is greatly weakened. In the actual use process, if the overall luminous efficiency of the scintillator panel is reduced, the flat panel detector will increase the X-ray irradiation dose in order to obtain a stronger signal or a clearer image, thereby causing damage to the examinee.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a scintillator layer material, a flexible scintillator panel, a preparation method of the flexible scintillator panel and application of the flexible scintillator panel. The structure of the scintillator layer material and the flexible scintillator panel can improve the luminous efficiency of the flexible scintillator panel together, improve the conversion efficiency of X rays and visible light in the scintillator panel, and further improve the performances of the detector such as sensitivity, dynamic range and resolution ratio.
The invention is realized by the following steps:
in a first aspect, the present invention provides a scintillator layer material, including a phosphor and a binder, the phosphor includes a rare metal-doped inorganic compound, and a two-dimensional structure of the phosphor includes any one of a polygon and a circle, the binder includes a resin precursor, and a refractive index of the resin precursor is equal to or greater than 1.52.
In a second aspect, the present invention provides a flexible scintillator panel comprising a light reflecting layer, a scintillator layer and a coupling layer in sequential contact covering, wherein the material of the scintillator layer comprises the scintillator layer material according to any one of the preceding embodiments.
In a third aspect, the present invention provides a method for preparing a flexible scintillator panel as in the previous embodiment, including layering and solidifying the materials of the scintillator layer and the light reflecting layer, and applying a coupling layer on the surface of the scintillator layer away from the light reflecting layer.
In a fourth aspect, the present invention provides a scintillator layer material according to any one of the preceding embodiments or a flexible scintillator panel according to the preceding embodiments for use in the field of the preparation of a flexible X-ray image sensor scintillator material.
The invention has the following beneficial effects:
the invention provides a scintillator layer material, a flexible scintillator panel, a preparation method and application thereof, which are characterized in that the shape structure of a phosphor is controlled, so that particles can be arranged more closely when the phosphor forms a scintillator layer, the interface distance is reduced, the filling density is improved, and the phenomenon of scintillator particle layering is avoided. In addition, by selecting a resin precursor having a high refractive index as the binder, the problem of light scattering at the interface between the "particle-binder-particle" due to the difference in optical properties between the binder and the phosphor can be reduced, and the overall emission intensity of the scintillator layer can be improved. The scintillator layer material with the effect is used for preparing the flexible scintillator panel, the reflecting layer can reflect visible light emitted by the scintillator layer in the direction far away from the coupling layer, and the visible light converted by the scintillator layer is reflected back as much as possible, so that the visible light extraction rate of the coupling layer is further improved. The preparation method of the flexible scintillator panel is simple, the flexible scintillator panel with high conversion efficiency between X rays and visible light can be prepared, and the flexible scintillator panel can be applied to a flexible X-ray image sensor.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.
FIG. 1 is a schematic structural diagram of a phosphor provided by the present invention;
FIG. 2 is a flow chart of a process for preparing a flexible scintillator panel according to the present invention;
FIG. 3 is a schematic diagram of the results of a flexible scintillator panel provided by the present invention;
FIG. 4 is a scanning electron microscope image of phosphors of different particle sizes provided by the present invention;
FIG. 5 is a scanning electron microscope image of scintillator layer materials made with different binders provided by the present invention;
FIG. 6 is a graph of luminescence spectra of scintillator panels made with different binders according to the present invention;
FIG. 7 is a scanning electron microscope image of scintillator layer materials made of phosphors of different particle sizes provided by the present invention;
FIG. 8 is a graph showing luminescence spectra of scintillator panels prepared in example 2 and comparative example 5, which are provided by the present invention;
FIG. 9 is a graph showing luminescence spectra of scintillator panels obtained in example 3 and comparative example 6, which are provided by the present invention;
FIG. 10 is a graph showing luminescence spectra of scintillator panels obtained in example 4 and comparative example 7 according to the present invention.
FIG. 11 is a graph showing luminescence spectra of scintillator panels obtained in examples 3 and 6 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The phenomenon of particle stratification is easy to occur on a scintillator panel by the currently prepared scintillator layer material, and mainly appears in the phenomenon that small-size particles are mainly used at the bottom of the scintillator panel, and large-and medium-size particles are mainly used from the middle to the top of the scintillator panel, so that the phenomenon of nonuniform light emission of a scintillator screen under the irradiation of X rays is caused, and the nonuniform light emission along the thickness direction is particularly obvious. In addition, the scintillator panel manufactured by the existing manufacturing method has low overall luminous efficiency, resulting in low conversion rate of X-rays to visible light, and therefore, the inventors have proposed the following solutions through research.
In a first aspect, the present invention provides a scintillator layer material, including a phosphor and a binder, the phosphor includes a rare metal-doped inorganic compound, and a two-dimensional structure of the phosphor includes any one of a polygon and a circle, the binder includes a resin precursor, and a refractive index of the resin precursor is equal to or greater than 1.52.
By controlling the shape and structure of the phosphor, the phosphor can be arranged more closely when forming the scintillator layer, thereby reducing the interface distance, improving the filling density and avoiding the layering phenomenon of the scintillator particles. In addition, by selecting a resin precursor having a high refractive index as the binder, the problem of light scattering at the "particle-binder-particle" interface due to the difference in optical properties between the binder and the phosphor can be reduced, and the overall emission intensity of the scintillator layer can be improved.
In an alternative embodiment, the ratio of the added mass of the phosphor to the binder is 1 to 10:1. by controlling the addition amount ratio of the phosphor and the binder within the above range, the phosphor and the binder have good binding and fixing ability, are uniformly dispersed, and are fully filled with the binder.
The ratio of the addition amount of the phosphor to the binder is preferably 2 to 8:1. it is understood that when the particle size of the phosphor is larger, the particle gap between the phosphors is also larger, and the addition amount of the phosphor needs to be reduced; when the particle diameter of the phosphor is small, the particle gap is small, and the addition amount of the phosphor can be relatively increased.
The mass ratio of the phosphor to the binder is more preferably 3 to 6:1. it is understood that when the viscosity of the resin precursor is large, the amount of the binder required between particles to prevent the phosphor particles from falling off is reduced, so the proportion of the phosphor increases; when the viscosity of the resin precursor is small, the amount of the binder required between the particles to prevent the phosphor particles from falling off increases, so the proportion of the phosphor decreases.
In an alternative embodiment, the phosphor comprises at least one of thallium doped cesium iodide, cerium doped gadolinium aluminum gallium garnet, terbium doped gadolinium oxysulfide, and cerium doped yttrium aluminum garnet.
Wherein the refractive index of thallium-doped cesium iodide at the wavelength of 550nm is 1.76, the refractive index of cerium-doped gadolinium aluminum gallium garnet at the wavelength of 530nm is 1.9, the refractive index of terbium-doped gadolinium oxysulfide at the wavelength of 545nm is 2.2, and the refractive index of cerium-doped yttrium aluminum garnet at the wavelength of 550nm is 1.82. The refractive index of the phosphor is within 1.9 +/-0.3, the difference between the refractive index of the phosphor and the refractive index of the resin precursor is small, the light loss is small in the process that the visible light converted by the phosphor is transmitted between the phosphor and the binder, and the luminous efficiency of the prepared scintillator panel is improved.
Preferably, the phosphor comprises at least one of cerium-doped gadolinium aluminum gallium garnet or terbium-doped gadolinium oxysulfide in order to facilitate absorption and generation of electrical signals by the silicon-based photodiode in the range of luminous intensity and luminous wavelength, since the silicon photodiode has the highest sensitivity to the wavelength band of 500-650 nm.
Preferably, in the phosphor, the two-dimensional structure is such that the total number of polygons having regular edges accounts for 70% or more, more preferably 80% or more of the total number of the phosphor.
In the phosphor, the "two-dimensional structure is a polygon having regular edges" may be a cube or a polyhedron having truncated corners on the basis of a cube.
Preferably, the sides of the polygon are 4 to 12. Accordingly, as shown in fig. 1, the two-dimensional structure of the phosphor may be any one of a quadrangle 201, a pentagon 202, a hexagon 203, a heptagon 204, an octagon 205, a nonagon 206, a decagon 207, an undecamoude 208, and a dodecagon 209. Further, when the phosphor is spherical, the two-dimensional structure of the phosphor may also be a circle 210.
More preferably, the polygon is a regular polygon.
The particle size of the phosphor is preferably 0.5 to 20 μm, more preferably 1 to 10 μm, and still more preferably 3 to 5 μm.
In the phosphor, the total number of the phosphors having a particle diameter of 3 to 5 μm is preferably 80% or more, more preferably 90% or more of the total number of the phosphors. The particle size of the phosphor is controlled within the above range, so that the particle stratification phenomenon in the scintillator panel can be avoided, and the particles can be arranged more closely, thereby reducing the interface distance and improving the packing density.
In addition, the inventor also finds that the finished scintillator panel prepared by the existing method is hard in texture and insufficient in flexibility, is difficult to be tightly attached when being attached to the surface of a base body, and particularly when the thickness of the substrate is small, the stress of the screen is easily transmitted to the substrate, so that the substrate is cracked due to long-term stress accumulation, the service life and the reliability of the whole equipment of the flat panel detector are greatly reduced, and therefore the following solutions are provided.
In an alternative embodiment, the binder includes any one of a polystyrene resin precursor, an epoxy resin precursor, a polymethylmethacrylate resin precursor, a cyclic olefin copolymer resin precursor, an organopolysiloxane resin precursor, a polyvinyl butyral resin precursor, a polycarbonate resin precursor, and an acrylic resin precursor.
Preferably, the binder includes any one of a polystyrene resin precursor, an epoxy resin precursor, a polymethyl methacrylate resin precursor, an organopolysiloxane resin precursor, a polyvinyl butyral resin precursor, or an acrylic resin precursor.
Preferably, the binder includes any one of a polystyrene resin precursor, an epoxy resin precursor, an organopolysiloxane resin precursor, or a polyvinyl butyral resin precursor.
Preferably, the binder comprises any one of a polystyrene resin precursor or an organopolysiloxane resin precursor; more preferably an organopolysiloxane resin precursor.
Preferably, the hardness (Shore D) of the binder is 30-50 DEG, and the transmittance is more than or equal to 92%, more preferably, the transmittance of the binder is more than or equal to 92.5%. The binder has better elasticity by controlling the Shore hardness of the binder within the range, and the prepared scintillator panel has stronger flexibility compared with the existing hard panel and can not generate continuous stress on a matrix.
Preferably, the binder has a curing temperature of 80 to 150 ℃ and forms a transparent elastomer after curing.
The currently used binder is easy to volatilize at high temperature, so that air is filled in the scintillator panel at the position where the binder should be filled between the fluorescent body and the fluorescent body, the fluorescent body is layered, the optical performance difference between the air and the fluorescent body is caused, visible light obtained by converting the fluorescent body is scattered or totally reflected when the visible light is transmitted to the air, and the luminous performance of the scintillator panel is further reduced. By controlling the curing temperature and the cured form of the binder, the flexibility of the scintillator panel is improved, the luminous efficiency of the scintillator panel is further improved, and the layering of the phosphor is prevented.
More preferably, the curing rate of the adhesive is more than or equal to 80% when the curing temperature of the adhesive is 80 ℃.
In an alternative embodiment, the method of preparing the scintillator layer material includes mixing the phosphor and the binder in proportion.
Preferably, as shown in fig. 2, the method for preparing the scintillator layer material includes: and placing the phosphor and the binder in a vacuum stirring defoaming machine for mixing to obtain the scintillator layer material.
Preferably, the mixing time is 1 to 3 hours, the vacuum degree is-0.001 to-0.01 MPa, and the stirring speed is 80 to 120rpm.
Preferably, the phosphor is further ground and sieved before mixing with the binder.
Grinding can refine phosphor particles and improve the light conversion efficiency of the phosphor. The grinding comprises the step of putting the fluorescent body into a vibration grinder for grinding for 5 to 8 hours at the grinding speed of 400 to 700rpm.
Preferably, the grinding comprises adding an alcohol solution for co-grinding, wherein the alcohol solution is absolute ethyl alcohol, and the adding amount ratio of the alcohol solution to the fluorescent body is 1:8 to 12.
The screening comprises placing the fluorophor in a vibration screening machine for screening, wherein the vibration frequency is 1500-2500 times/min, the screening time is 20-40 min, and the mesh number of a sample separation screen is 900-2800 meshes.
Preferably, the mesh number of the sample separation screen is 900 mesh, 1000 mesh, 1800 mesh, 2000 mesh, 2300 mesh and 2800 mesh.
Preferably, the screening method further comprises mixing the fluorescent material with an alcohol solution to form a suspension, wherein the alcohol solution is absolute ethyl alcohol, and the adding amount ratio of the alcohol solution to the fluorescent material is 1-2: 1, mixing for 8-12 min.
In a second aspect, as shown in fig. 3, the present invention provides a flexible scintillator panel comprising a light reflecting layer 1, a scintillator layer 2 and a coupling layer 3 in sequential contact coverage, wherein the material of the scintillator layer 2 comprises the scintillator layer material according to any one of the previous embodiments.
The reflector layer 1 is as the incident surface of X ray, when X ray passed reflector layer 1 and got into scintillator layer 2, X ray shined the fluorophor surface, it propagates in scintillator layer 2 to be converted into visible light by the fluorophor, because a plurality of surfaces of scintillator can send visible light to different directions, when visible light propagates towards the reflector layer direction, reach reflector layer 1 surface and can be reflected back, until light along coupling layer 3 spreads out, because the reflection of light effect of reflector layer 1 has increased the light-emitting rate of coupling layer 3 direction, the output intensity of the light that has sent at coupling layer 3 has been improved, and then the whole luminous intensity of scintillator panel has been improved.
In an alternative embodiment, the material of the light reflecting layer 1 includes at least one of a nano high diffuse reflection material, a metal thin film, or an inorganic oxide.
Preferably, the nano high diffuse reflection material includes, but is not limited to, any one of nano borosilicate powder suspension, nano tetrafluoroethylene particle suspension and nano silicon dioxide powder suspension; metal films include, but are not limited to, aluminum or silver foils; inorganic oxides include, but are not limited to, any of titanium dioxide, magnesium oxide, or barium sulfate.
Preferably, in order to avoid that the visible light propagating towards the reflective layer 1 directly passes through the reflective layer 1, which results in the decrease of the light extraction rate of the coupling layer 3, the total reflectivity of the reflective layer 1 in the visible light band is greater than or equal to 94%.
Preferably, the coupling layer 3 is an optical extraction layer, and in an actual use process, the coupling layer 3 is connected with a substrate of the image sensor. The material of the coupling layer 3 includes any one of thermosetting resin or light-curing resin.
Preferably, the thickness of the light reflecting layer 1 is 40 to 150 μm, the thickness of the scintillator layer 2 is 20 to 200 μm, and the thickness of the coupling layer 3 is 10 to 30 μm.
Preferably, the thickness of the scintillator layer 2 is 20 to 100 μm when it is necessary to improve the image resolution of the scintillator panel. When the scintillator layer thickness is small, a clear image can be obtained, and the image resolution is high.
Or preferably, the thickness of the scintillator layer 2 is 150 to 200 μm when it is necessary to increase the light emission intensity of the scintillator panel. When the thickness of the scintillator is larger, the luminous intensity is higher.
In a third aspect, the present invention provides a method for manufacturing a flexible scintillator panel according to the foregoing embodiment, as shown in fig. 2, including layering and solidifying the materials of the scintillator layer and the light reflecting layer, and applying a coupling layer on the surface of the scintillator layer away from the light reflecting layer.
In an alternative embodiment, solidifying the material of the scintillator layer and the light reflecting layer in layers comprises:
when the material of the reflecting layer is a metal film, the material of the scintillator layer is coated on the surface of the reflecting layer, and then pre-curing and pressure curing are sequentially carried out.
When the material of the reflecting layer is inorganic oxide, the scintillator layer material is subjected to pre-curing and pressure curing in sequence after being filled into a mold, and then the inorganic oxide is coated on the surface of the scintillator layer in a blade mode.
When the material of the reflecting layer is a nano high diffuse reflection material, the scintillator layer material is subjected to pre-curing and pressure curing in sequence after being molded, and then the nano high diffuse reflection material is sprayed on the surface of the scintillator layer.
According to the invention, the scintillator layer is pre-cured and pressure cured, the pre-cured body can form a non-flowing state body, resin overflow is avoided during pressure curing, and the pressure curing is facilitated to form a scintillator layer structure with uniform internal structure and better appearance. The pressurizing curing forming process can further compact the fluorescent bodies in the curing process, and the fluorescent bodies are closely arranged again under the condition that gaps among the fluorescent bodies are small, so that the interface distance is reduced, the filling density is further improved, the particle layering phenomenon of the fluorescent bodies is reduced, the interface light scattering of particle-binder-particle is reduced, and the overall luminous intensity of the scintillator layer is further improved.
Preferably, the pre-curing temperature is 80-110 ℃, and the pre-curing time is 0.5-1 h.
Preferably, the curing temperature is 120-150 ℃, the curing time is 1-3 h, and the curing pressure is 0.5-5 MPa; more preferably, the temperature of curing is 150 ℃.
In an alternative embodiment, the coating method of the coupling layer includes:
when the material of the coupling layer is thermosetting resin, the material of the coupling layer is coated on the surface of the scintillator layer far away from the light reflecting layer for pre-curing and pressure curing.
And when the material of the coupling layer is light-cured resin, coating the material of the coupling layer on the surface of the scintillator layer far away from the reflecting layer for ultraviolet irradiation curing.
Preferably, the ultraviolet light curing has the wavelength of 310 to 395nm and the energy of 4 to 10J/cm 3 。
In a fourth aspect, the present invention provides a scintillator layer material according to any one of the preceding embodiments or a flexible scintillator panel according to the preceding embodiments for use in the field of the preparation of scintillator materials for X-ray image sensors.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
The embodiment provides a scintillator layer material, and a preparation method thereof is as follows:
s1, grinding: 100 parts by weight of terbium-doped gadolinium oxysulfide powder and 10 parts by weight of absolute ethyl alcohol are added into a vibration grinding machine to be ground, the grinding time is 8 hours, and the grinding rotating speed is 600rpm.
S2, screening: 100 parts by weight of the phosphor obtained by the above grinding and 120 parts by weight of absolute ethyl alcohol were put in a stirrer and stirred and mixed at normal temperature to form a suspension, and the mixing time was 10min. And mixing, pouring the suspension into a vibration screening machine, screening for 30min at a vibration frequency of 2000 times/min, wherein the number of the sample separation screens is 6 layers including 900 meshes, 1000 meshes, 1800 meshes, 2000 meshes, 2300 meshes and 2800 meshes, and selecting powder with the mesh number of below 2300 meshes for later use.
S3, mixing
And (3) mixing 100 parts by weight of the phosphor obtained in the step (S2) and 20 parts by weight of the organopolysiloxane resin precursor in a vacuum stirring defoaming machine for 2 hours at a vacuum degree of-0.01 MPa and a stirring speed of 100rpm to obtain the liquid scintillator layer material.
Example 2
This example provides a scintillator layer material, which is prepared by the same method as in example 1, but differs from the step S1 only in the following specific way:
s1, grinding: 100 parts by weight of cerium-doped gadolinium aluminum gallium garnet powder and 10 parts by weight of absolute ethyl alcohol are added into a vibration grinding machine for grinding for 5 hours at a grinding speed of 500rpm.
Example 3
The embodiment provides a flexible scintillator panel, wherein the material of the reflecting layer is a metal film and an aluminum foil reflector, and the thickness of the reflecting layer is 200 μm; the material of the scintillator layer was the scintillator layer material provided in example 1, and the thickness was 100 μm; the coupling layer is made of thermosetting resin, specifically an organopolysiloxane resin precursor, and has a thickness of 20 μm. The preparation method of the flexible scintillator panel comprises the following steps:
s1, layered solidification of materials of the scintillator layer and the light reflecting layer
The scintillator layer material provided in example 1, with an aluminum foil reflector laid flat on the blade coater plate, adjusted to a height of 0.1mm and a blade thickness of 0.1mm, was pre-cured by heating the material to 80 ℃ for 1h. And raising the temperature to 150 ℃, and carrying out pressure curing, wherein the curing pressure is 1MPa, and the curing time is 3h.
S2, coating the material of the coupling layer
Spreading the material obtained in the step S1 on a flat plate of a blade coating machine, wherein the surface to be coated is the surface of the scintillator layer far away from the reflective layer, adjusting the height of a scraper to be 0.02mm, and blade-coating an organopolysiloxane resin precursor with the thickness of 0.02mm to form a coupling layer, heating the material to 80 ℃ for precuring, wherein the precuring time is 0.5h, raising the temperature to 150 ℃, and heating and curing for 1h.
Example 4
The embodiment provides a flexible scintillator panel, wherein the material of the light reflecting layer is inorganic oxide and titanium dioxide, and the thickness of the light reflecting layer is 200 μm; the material of the scintillator layer was the scintillator layer material provided in example 1, and the thickness was 100 μm; the coupling layer is made of light-cured resin, specifically polyurethane acrylate, and has a thickness of 20 μm. The preparation method of the flexible scintillator panel comprises the following steps:
s1, layered solidification of materials of the scintillator layer and the light reflecting layer
The scintillator layer material provided in example 1 was loaded into a mold with a groove having a depth of 0.1mm, and the mold and scintillator layer material were heated together to 80 ℃ for precuring for 0.5h. And raising the temperature to 150 ℃, carrying out pressure curing, wherein the curing pressure is 4MPa, the curing time is 3h, and demolding after curing to obtain the scintillator layer. Titanium dioxide was coated on the surface of the scintillator layer by a doctor blade method.
S2, coating the material of the coupling layer
Spreading the material obtained in the step S1 on a flat plate of a blade coater, wherein the surface to be coated is the surface of a scintillator layer far away from a reflecting layer, adjusting the height of a scraper to be 0.02mm, blade-coating a polyurethane acrylate precursor with the thickness of 0.02mm to form a coupling layer, and then carrying out ultraviolet irradiation curing, wherein the wavelength of ultraviolet light is 310-395 nm, and the energy is 4J/cm 3 And the curing time is 20s.
Example 5
The embodiment provides a flexible scintillator panel, wherein a reflective layer is made of a nano high diffuse reflection material and a nano borosilicate powder suspension, and the thickness of the reflective layer is 200 micrometers; the material of the scintillator layer was the scintillator layer material provided in example 1, and the thickness was 100 μm; the coupling layer is made of light-cured resin, specifically polyurethane acrylate, and has a thickness of 20 μm. The preparation method of the flexible scintillator panel comprises the following steps:
s1, layered solidification of materials of the scintillator layer and the light reflecting layer
The scintillator layer material provided in example 1 was loaded into a mold with a groove having a depth of 0.1mm, and the mold and scintillator layer material were heated together to 80 ℃ for precuring for 0.5h. And raising the temperature to 150 ℃, carrying out pressure curing, wherein the curing pressure is 3MPa, the curing time is 3h, and demoulding to obtain the scintillator layer after curing. And spraying the nano high-diffuse-reflection material on the surface of the scintillator layer by adopting a spraying method.
S2, coating the material of the coupling layer
Spreading the material obtained in the step S1 on a flat plate of a blade coater, wherein the surface to be coated is the surface of a scintillator layer far away from a reflecting layer, adjusting the height of a scraper to be 0.02mm, blade-coating a polyurethane acrylate precursor with the thickness of 0.02mm to form a coupling layer, and then carrying out ultraviolet irradiation curing, wherein the wavelength of ultraviolet light is 310-395 nm, and the energy is 4J/cm 3 And the curing time is 20s.
Example 6
This embodiment provides a flexible scintillator panel having the same structure as embodiment 3, differing only in scintillator layer material. The scintillator layer material used in this example was a mixture of the powders obtained in examples 1 and 2, in which terbium-doped gadolinium oxysulfide powder: the proportion of cerium-doped gadolinium aluminum gallium garnet powder is 80: and 20, mixing the two for 5h to obtain the scintillator layer material. The scintillator layer material was then used to prepare a flexible scintillator panel according to the method of example 3.
Comparative example 1
This comparative example provides a scintillator layer material prepared in the same manner as in example 1 except that the phosphor powder having a mesh size of 1800 mesh or less was selected after sieving.
Comparative example 2
This comparative example provides a scintillator layer material prepared in the same manner as in example 1 except that the phosphor powder having a mesh number of 2800 mesh or less after sieving was selected.
Comparative example 3
This comparative example provides a flexible scintillator panel that was prepared in the same manner as example 3, except that the binder in the scintillator layer was an acrylic resin.
Comparative example 4
This comparative example provides a flexible scintillator panel that was prepared in the same manner as example 3, except that the phosphor in the scintillator layer was the phosphor provided in comparative example 1.
Comparative example 5
This comparative example provides a flexible scintillator panel that was prepared in the same manner as example 3, except that there was no light-reflecting layer.
Comparative example 6
This comparative example provides a flexible scintillator panel that was prepared in the same manner as example 4, except that there was no light reflecting layer.
Comparative example 7
This comparative example provides a flexible scintillator panel that was prepared in the same manner as example 5, except that there was no light-reflecting layer.
Test example 1
The phosphor powders obtained by sieving in example 1 and comparative examples 1 and 2 were examined for the size of the particle shape, and observed by a scanning electron microscope to obtain the results shown in FIG. 4.
In FIG. 4, a is a microscopic image of the phosphor sieved in example 1, b is a microscopic image of the phosphor sieved in comparative example 1, and c is a microscopic image of the phosphor sieved in comparative example 2. As can be seen from FIG. 4, the phosphor obtained by sieving in comparative example 1 had a small particle size and an average particle size of about 2.5 μm, the phosphor obtained by sieving in comparative example 2 had a large particle size and an average particle size of about 10 μm, and the phosphor obtained by sieving in example 1 had a moderate particle size and an average particle size of about 5 μm.
Test example 2
1) The scintillator layer materials obtained in example 3 and comparative example 3 were examined and observed by a scanning electron microscope, and the results shown in fig. 5 were obtained.
In fig. 5, a is a microscopic image of the scintillator layer material obtained in example 3, and b is a microscopic image of the scintillator layer material obtained in comparative example 3. As can be seen from fig. 5, in example 3, the use of the organopolysiloxane resin precursor allows the interparticle binder to be filled more sufficiently. While comparative example 3 uses an acrylic resin as a binder, air gaps exist between phosphor particles.
2) The flexible scintillator panel prepared in example 3 and the scintillator panel prepared in comparative example 3 were placed between an X-ray source and a spectrometer probe, X-rays were incident from the end face of the reflective layer, the spectrometer probe was attached to the coupling layer, and spectral data during X-ray irradiation was collected by a spectrometer to obtain a luminescence emission peak and an intensity distribution curve, as shown in fig. 6.
As can be seen from fig. 6, the light loss of the visible light converted by the phosphor during the propagation between the phosphor and the organopolysiloxane resin is smaller than that in the phosphor and the acrylic resin, and the scintillator panel produced has a higher light emission intensity.
Test example 3
The scintillator layer materials obtained in example 3 and comparative example 4 were examined and observed by a scanning electron microscope, and the results shown in FIG. 7 were obtained.
In fig. 7, a is a microscopic image of the scintillator layer material obtained in example 3, and b is a microscopic image of the scintillator layer material obtained in comparative example 4. And measuring the total area of the adhesive region and the total area of the phosphor particles according to the image scale to obtain the density ratio. In order to reduce the error, 10 samples under the same conditions were randomly selected for statistics, and the average value was calculated to obtain the detection results shown in table 1.
TABLE 1
| BondingTotal area of agent region | Total area of phosphor particles | Density ratio | |
| Example 4 | 126μm 2 | 224μm 2 | 1.78 |
| Comparative example 4 | 154μm 2 | 196μm 2 | 1.27 |
From the data, the scintillator layer material provided by the embodiment of the invention has high density, the visible light conversion rate is improved, and the light output quantity is increased.
Test example 4
The flexible scintillator panels provided in examples 3 to 6 and the scintillator panels prepared in comparative examples 5 to 7 were placed between an X-ray source and a spectrometer probe, and X-rays were incident from the end face of the reflective layer, whereas X-rays were incident from the end face of the scintillator layer when the reflective layers were not present in comparative examples 5 to 7. The spectrometer probe is tightly attached to the coupling layer, and the spectrometer collects spectral data during X-ray irradiation to obtain a luminous emergent peak and an intensity distribution curve, as shown in the results of FIGS. 8-11.
As can be seen from fig. 8 to 10, when the scintillator panel is not provided with the reflective layer, the light intensity of the emitted visible light is significantly reduced, and the light-emitting intensity of the flexible scintillator panel provided in the embodiment of the present invention is large.
In fig. 11, the solid line shows the results of the experiment in example 3, and the broken line shows the results of the experiment in example 6. As can be seen from fig. 11, the flexible scintillator panels prepared in examples 3 and 6 both have better light extraction performance.
In summary, the scintillator layer material, the flexible scintillator panel, the preparation method thereof and the application thereof provided by the invention have the following advantages:
1. by controlling the shape and structure of the fluorescent body, the fluorescent body can be arranged more closely among particles when forming the scintillator layer, so that the interface distance is reduced, the filling density is improved, and the phenomenon of particle layering of the scintillator is avoided.
2. The refractive index of the selected phosphor is within 1.9 +/-0.3, the difference between the refractive index of the phosphor and the refractive index of the resin precursor is small, the light loss is small in the process that visible light converted by the phosphor is transmitted between the phosphor and the binder, and the luminous efficiency of the prepared scintillator panel is improved.
3. By selecting a resin precursor with a high refractive index as the binder, the problem of light scattering at the interface between particles and the binder due to the difference in optical properties between the binder and the phosphor can be reduced, and the overall luminous intensity of the scintillator layer can be improved.
By controlling the curing temperature and the cured form of the binder, the flexibility of the scintillator panel is improved, the luminous efficiency of the scintillator panel is further improved, and the layering of the phosphor is prevented.
The binder has better elasticity by controlling the Shore hardness of the binder within the range, and the prepared scintillator panel has stronger flexibility compared with the existing hard plate and can not generate continuous stress on a matrix. The organic polysiloxane resin is selected as the fluorescent particle binder, so that a scintillator layer elastomer with excellent flexibility can be formed after curing, the scintillator layer elastomer is convenient to be attached to a rigid or flexible substrate, and stress accumulation is reduced.
4. The incident surface of reflector layer conduct X ray, when X ray passed the reflector layer and got into the scintillator layer, X ray shines the fluorophor surface, it spreads at the scintillator in-layer to be called visible light by the fluorophor conversion, because a plurality of surfaces of scintillator can send visible light to equidirectional emission, when visible light propagated towards the reflector layer direction, reach the reflector layer surface and can be reflected back, until light spreads along the coupling layer, because the reflection of light effect of reflector layer has increased the light-emitting rate of coupling layer direction, the output intensity of the light that sends at the coupling layer has been improved, and then the whole luminous intensity of scintillator panel has been improved.
5. According to the invention, the scintillator layer is pre-cured and pressure cured, the pre-cured body can form a non-flowing state body, resin overflow is avoided during pressure curing, and the pressure curing is facilitated to form a scintillator layer structure with uniform internal structure and better appearance. The pressurizing curing forming process can further compact the fluorescent bodies in the curing process, and the fluorescent bodies are closely arranged again under the condition that gaps among the fluorescent bodies are small, so that the interface distance is reduced, the filling density is further improved, the particle layering phenomenon of the fluorescent bodies is reduced, the interface light scattering of particle-binder-particle is reduced, and the overall luminous intensity of the scintillator layer is further improved.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The scintillator layer material is characterized by comprising a phosphor and a binder, wherein the phosphor comprises a rare metal-doped inorganic compound, the two-dimensional structure of the phosphor comprises any one of a polygon and a circle, the binder comprises a resin precursor, and the refractive index of the resin precursor is not less than 1.52.
2. The scintillator layer material according to claim 1, wherein the mass ratio of the phosphor to the binder is 1 to 10:1, preferably 2 to 8:1, more preferably 3 to 6:1.
3. the scintillator layer material of claim 1, wherein the phosphor comprises at least one of thallium doped cesium iodide, cerium doped gadolinium aluminum gallium garnet, terbium doped gadolinium oxysulfide, and cerium doped yttrium aluminum garnet;
preferably, the phosphor comprises at least one of cerium-doped gadolinium aluminum gallium garnet or terbium-doped gadolinium oxysulfide;
preferably, in the phosphor, the total number of polygons having a two-dimensional structure with regular edge angles accounts for 70% or more, more preferably 80% or more of the total number of the phosphor;
preferably, the particle size of the phosphor is 0.5 to 20 μm, more preferably, the particle size of the phosphor is 1 to 10 μm, more preferably, the particle size of the phosphor is 3 to 5 μm;
preferably, in the phosphor, the total number of phosphors having a particle diameter of 3 to 5 μm accounts for 80% or more, more preferably 90% or more of the total number of the phosphors;
preferably, the side length of the polygon is 4-12; more preferably, the polygon is a regular polygon.
4. The scintillator layer material according to claim 1, wherein the binder comprises any one of a polystyrene resin precursor, an epoxy resin precursor, a polymethyl methacrylate resin precursor, a cyclic olefin copolymer resin precursor, an organopolysiloxane resin precursor, a polyvinyl butyral resin precursor, a polycarbonate resin precursor, and an acrylic resin precursor;
preferably, the binder comprises any one of a polystyrene resin precursor, an epoxy resin precursor, a polymethyl methacrylate resin precursor, an organopolysiloxane resin precursor, a polyvinyl butyral resin precursor, or an acrylic resin precursor;
preferably, the binder comprises any one of a polystyrene resin precursor, an epoxy resin precursor, an organopolysiloxane resin precursor, or a polyvinyl butyral resin precursor;
preferably, the binder includes any one of a polystyrene resin precursor or an organopolysiloxane resin precursor; more preferably an organopolysiloxane resin precursor;
preferably, the Shore hardness of the binder is 30-50 degrees, the transmittance is not less than 92%, and more preferably, the transmittance of the binder is not less than 92.5%;
preferably, the curing temperature of the adhesive is 80-150 ℃, and the transparent elastomer is formed after curing; more preferably, when the curing temperature of the adhesive is 80 ℃, the curing rate of the adhesive is more than or equal to 80%.
5. A flexible scintillator panel comprising a light reflecting layer, a scintillator layer and a coupling layer in sequential contact coverage, the material of the scintillator layer comprising the scintillator layer material of any one of claims 1 to 4.
6. The flexible scintillator panel of claim 5, wherein the material of the light reflecting layer comprises at least one of a nano-scale high diffuse reflectance material, a thin metal film, or an inorganic oxide;
preferably, the total reflectivity of the light reflecting layer in a visible light wave band is more than or equal to 94 percent;
preferably, the material of the coupling layer includes any one of a thermosetting resin or a photo-curing resin;
preferably, the thickness of the light reflecting layer is 40-150 μm, the thickness of the scintillator layer is 20-200 μm, and the thickness of the coupling layer is 10-30 μm;
preferably, when it is required to improve the image resolution of the scintillator panel, the thickness of the scintillator layer is 20 to 100 μm;
or preferably, when the luminous intensity of the scintillator panel needs to be improved, the thickness of the scintillator layer is 150 to 200 μm.
7. A method of manufacturing a flexible scintillator panel as claimed in claim 5 or 6 including solidifying the scintillator layer material and the light reflecting layer material in layers and applying a coupling layer to the surface of the scintillator layer remote from the light reflecting layer.
8. The method of claim 7, wherein solidifying the scintillator layer material and the light reflecting layer material in layers comprises:
when the material of the reflecting layer is a metal film, coating the material of the scintillator layer on the surface of the reflecting layer, and then sequentially carrying out pre-curing and pressure curing;
when the material of the reflecting layer is inorganic oxide, the scintillator layer material is subjected to pre-curing and pressure curing in sequence after being subjected to die filling, and then the inorganic oxide is coated on the surface of the scintillator layer in a blade mode;
when the material of the reflecting layer is a nano high-diffuse reflection material, the material of the scintillator layer is filled into a mold and then is sequentially subjected to pre-curing and pressure curing, and then the nano high-diffuse reflection material is sprayed on the surface of the scintillator layer;
preferably, the pre-curing temperature is 80-110 ℃, and the pre-curing time is 0.5-1 h;
preferably, the curing temperature is 120-150 ℃, the curing time is 1-3 h, and the curing pressure is 0.5-5 MPa; more preferably, the temperature of the curing is 150 ℃.
9. The method for preparing the optical element according to claim 8, wherein the method for coating the coupling layer comprises:
when the material of the coupling layer is thermosetting resin, applying the material of the coupling layer to the surface of the scintillator layer far away from the light reflecting layer for pre-curing and curing;
when the material of the coupling layer is light-cured resin, the material of the coupling layer is coated on the surface of the scintillator layer far away from the light reflecting layer to be cured by ultraviolet irradiation;
preferably, the ultraviolet light cured by ultraviolet light has the wavelength of 310-395 nm and the energy of 4-10J/cm 3 。
10. Use of the scintillator layer material according to any of claims 1 to 4 or the flexible scintillator panel according to claim 5 or 6 in the field of the preparation of scintillator materials for flexible X-ray image sensors.
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